In developing the rules we looked for general issues that are universal and were wary of small numbers of specifics that could be interpretated in several ways. In this way we can gt the core game working well. If alter we then find funky ways to model a few specifics we can always add them."When the serried Macedonian ranks presented their enormously long spears it was like a shield-wall, and when the Romans after fruitlessly hurling their javelins, drew their swords they could not get to close quarters, nor could they hack off the spear-heads; if they did succeed in cutting or breaking any off, the splintered shafts kept their places amongst the points of the uninjured ones and the palisade remained unbroken. Another thing which helped the enemy was.....[that] they had not to attack or retire over a wide stretch of ground, which generally disorders the ranks."
Hence the above section we felt was a good major item for the rules mechanics ... Romans are Swordsmen in the rules and this is a + if you can "get in amongst them" but useless otherwise. If and when you play the game you will see that this is exactly how the mechanics are set up. If you can DISRUPT the phalanx ther Romans will do well, if the Phalanx remains STEADY it is very hard indeed and the Phalanx has the edge.
As for push backs etc. we decided that it was not the push backs that cause problems per se - so got rid of the old fashioned + for doing this - but rather the disruption effects on either side if this were to happen. In addition in game mechanics we started with push backs and actually monitored the amount of time in a game spent doing it and re-arranging figures. We found that it was consuming huge amounts of time and a fundamental reason for slowing down war games - for little benefit in game terms. So we dropped it and the speed of play and wrapping of effects into what really mattered - whether you were dirsupted or not - has been a huge plus stated by players. The speed of game is quick very much because of this.
However you do the rules there are one or two examples from history that can be interpreted in different ways. The example you give could be interpreted in several ways. Whether the battle disruption occured because of terrain or push backs or the combination is argauble.
We settled for the terrain effect for the following reason. If push backs were common and they caused disruption often then we would hear about it far more frequently in any battle with pahlanxes. We don't we hear more about this exception. When anaylsing history it is as importnat to look at what hassn't been recorded and ask oneself why as it is to look at what has been written down and adjust it for the grandification that is natural to any author with incentivesto do more than just record accurately. The mentining of uneveness of ground is however quite distinct - so we added a 4th terrain level that affects ionly close order troops to represent this. Again this has worked well in game terms.
As for the views from afar it is hard to say what is a "push back" or a "local collapse with follow ups". The latter in fact is much more likely to cause problems - like a scrum following up on a falling over by the opposition. We therefore also represent pursuits which can cause a battle line to have isolated BGs that are now vulnerable - a broader form of dispruption from "following up".
Si